This invention relates to devices of the class used for joining fluid carrying conduits. More specifically, the invention is a coupler used to connect elastomeric irrigation tubing or hoses, meaning either the connecting of two lengths of tubing or hose to each other, or the connecting of one tube or hose to a threaded plumbing fixture.
Underground lawn sprinkling systems and other underground irrigation systems generally are comprised of varying lengths of polyethylene hose or tube. Although polyvinyl chloride (PVC) tube is a widely used material for interior plumbing systems, PVC is not suitable for such underground systems in all climates, as PVC is rigid and cannot accomodate changes in dimension caused by freeze-thaw cycles. The PVC pipe system must be drained of all water every cold season by draining or blowing, in order to prevent rupture by the expansion of frozen water. Polyethylene can, however, accomodate such temperature changes, so it has become the predominant material in such underground systems. Polyethylene poses a problem for installers and repairers, though. After underground installation, whenever it is necessary to join two lengths of polyethylene tube or hose, a coupling must be used, of the type that has two nipples to fit into each end of the hoses to be joined. To install the coupling, the installer very frequently has to lift and gently bend one end of hose, in order to shorten that length of hose enough to fit over the end of a nipple and then be pushed over the length of the nipple. Even if due care is exercised in the installation, while so bending the hose it often kinks, which substantially weakens the integrity of polyethylene hose. This in turn necessitates expensive and time consuming hose replacement and further repair.
Therefore, there is a need for a coupler that can be installed in such polyethylene irrigation systems without the need to bend up one of the hose sections to be joined and run the risk of kinking the section. It is the primary object of the present invention to meet this need by providing a coupling that can be dimensionally shortened to fit into a gap between two sections of hose to be joined, and then be dimensionally lengthened so that each nipple can be thrust into each of the hose ends. The present invention accomplishes this by the use of a three component assembly, namely an outer or female nippled component, an inner or male nippled component and a locking cap. The inner component can slide with respect to the outer component, thus shortening or lengthening the complete coupling. Thus, the assembled coupling can be placed in a cut gap between two lengths of hose, one nipple can be inserted into the first end of hose and the coupling can be pulled out or expanded so that the second nipple can be inserted into the second hose end. By being able to expand in length, the coupling does away with the need to lift and bend one end of hose, eliminating that as a source of potential hose kinks.
Another object of the invention is to be able to securely affix a lock cap without the need for adhesives. This has been accomplished by the use of the technique of untrasonic welding. This feature eliminates the need for adhesives, which are toxic, expensive and messy to handle.